This invention relates to an apparatus for preventing gear buzzing in shifting to reverse in a manual transmission.
Conventionally, the reverse gear means in a manual transmission has a selective sliding-gear intermeshing mechanism driven by a reverse idler gear and is not provided with a synchronizing mechanism such as a synchronous meshing mechanism like the forward gear means, because shifting to reverse is as a rule conducted while a vehicle is stationary.
In the above-described conventional transmission, in particular when it is subjected to quick shifting into reverse, the gears clash with each other when the reverse gear meshes with the reverse idler gear because the inertial rotation of the input shaft is still in progress, whereby gear buzzing is generated which gives an unpleasant feeling to the driver and may adversely affect the feeling of shifting. In addition, the clash of gears at such time sometimes causes gear teeth breakage. It might easily be considered that a synchronous meshing mechanism should be provided exclusively for the reverse gear means in order to prevent such gear buzzing. However, such a measure would not be beneficial because it is difficult to secure the space required for providing the synchronous meshing mechanism, costs would be raised, and the weight increased.
On the other hand, Japanese Utility Model Unexamined Publications Nos. 79665/1984 and 75964/1984 disclose apparatuses for preventing the gear buzzing in shifting to reverse without providing the reverse gear means with a synchronous meshing mechanism. Both of these publications disclose a technique of shifting a shift head for the forward gear means which is located adjacent to the reverse gear means by a predetermined amount at the time of shifting to reverse. This shifting of the shift head stops or lowers the inertial rotation of the input shaft by utilizing the synchronous meshing mechanism provided for the forward gear means, thereby preventing the gear buzzing.
However, in the technique disclosed in the above-described Japanese Utility Model Unexamined Publication No. 79665/1984, it is necessary, when shifting the shift head for the forward gear means by a predetermined amount, to move an interlock plate in the selecting direction as well as shifting the gear lever to the reverse gear position, because the inner lever of a shift-and-select lever shaft moves in the selecting direction through the movement of the interlock plate in the selecting direction. Therefore, this structure limits the driver's ability to quickly shift the shift head for the forward gear means by a predetermined amount.
On the other hand, in the technique disclosed in the above-described Japanese Utility Model Unexamined Publication No. 75964/1984, it is necessary, when shifting the shift head for the forward gear means by a predetermined amount, to intermesh the inner lever of the shift-and-select lever shaft with the lock-bolt of the transmission case as well as shifting the gear lever to the reverse gear position, because the inner lever of the shift-and-select lever shaft moves in the selecting direction through the intermeshing with the lock-bolt. Therefore, this structure also limits the ability to quickly shift the shift head for the forward gear means by a predetermined amount.